Hydroxy acids (HAs) and retinoids have been proven to deliver cosmetic benefits, such as improvement in the appearance of photodamaged or naturally aged skin, skin lightening, treatment of age spots, etc. Unfortunately, their use at high concentrations may occasionally be associated with skin irritation, e.g. skin redness and stinging sensation upon application. The irritation can be ameliorated by lowering the amount of an active ingredient in the composition or by reducing the active's penetration through the skin. A serious drawback of both approaches is that the efficacy is impaired. The HA related irritation can be reduced by raising the composition's pH but this method yields reduced efficacy due to a decreased HA penetration through the skin. It is desirable to reduce or eliminate the irritation potential of HAs and/or retinoids while maintaining their efficacy.
European Patent Application 0631722 (Johnson & Johnson) discloses the use of glycolic acid to reduce irritation of the skin by retinol. U.S. Pat. No. 5,252,604 (Nagy et al.) teaches the use of tocopherols for retinoic acid induced irritation. U.S. Pat. No. 5,516,793 (Duffy) discloses the use of ascorbic acid to ameliorate the irritation caused by various topical ingredients, including HAs and retinoids.
U.S. Pat. No. 5,476,661 (Pillai et al.) discloses cosmetic compositions containing 25-hydroxycalciferol and a lipid ingredient. Numerous optional ingredients are listed among which are mentioned HAs and/or retinoids and unsaturated fatty acids, such as gamma linolenic acid (GLA). Pillai et al. do not address the problem of skin irritation, do not teach the use of any agent for reducing skin irritation and do not teach the use of Trichodesma lanicum seed extract.
European Patent Application 0416855 (Efamol) discloses treatment of skin damage due to radiotherapy with gamma linolenic acid (GLA) and also teaches a variety of suitable plant sources of GLA, including Borage species. PCT application WO 90/07331 (Went) teaches treatment of inflammation arising from arthritis or headache by topical application of GLA; borage seed is taught as a suitable source. European Patent Application 0173478 (Efamol) discloses treatment of inflammatory skin disorders with compositions containing GLA and glucocorticoids; borage species such as Borago officinalis is mentioned as a rich source of GLA. French patent 2,704,390 (Boiron) discloses an oral supplement containing borage seed oil to provide anti-aging benefits to skin. French patent 2,604,624 (Parfums Rochas) discloses skin care compositions containing polyunsaturated carboxylic acids, such as GLA; borage is said to be rich in GLA. Great Britain Patent 2,271,928 (Laing) discloses the use of borage family plant extracts for alleviation of skin disorders and irritations.
U.S. Pat. No. 5,445,822 (Bracco) discloses cosmetic compositions containing a mixture of polyunsaturated acids' triglycerides, wherein the fatty acids include stearidonic acid. Borage oil is listed as a suitable oil. Role of lipids (triglycerides) in anti-inflammatory processes is described. Tollesson et al., "Transepidermal Water Loss and Water Content in the Stratum Corneum in Infantile Sebhorroeic Dermatitis", Acta Derm Venereol (Sweden), February 1993, 73 (1), p. 18-20, disclose the use of topically applied borage oil for treatment of sebhorroeic dermatitis. Bahmer et al., "Treatment of Atopic Dermatitis with Borage Seed Oil (Glandol)--A Time Series Analytic Study", Kinderarztl Prax (Germany), October 1992, 60 (7), p. 199-202, disclose the use of borage oil for the treatment of atopic dermatitis.
U.S. Pat. No. 5,690,947 (Habif et al.) disclose the use of borage seed oil for alleviating irritation caused by hydroxyl acids or retinoids.
U.S. Pat. No. 5,158,975 (Guichardant et al.) discloses the use of stearidonic acid for inhibiting leukotrienes. The composition may be used topically for treating skin inflammations, e.g. acne, eczema or psoriasis. Coupland et al. disclose in papers presented at IFSCC on 22-25 Oct. 1996 (Sydney) that stearidonic acid is known to possess anti-inflammatory properties and that Crossessential SA 6 (Trichodesma lanicum) is a powerful moderator of UV-induced inflammation. Numerous compounds exist, however, that are able to reduce UV-induced irritation, but not hydroxy acid or retinoid-induced irritation (see Example 4).
Trichodesma lanicum is a different plant from borage seed oil, albeit both belong to the Boragenous family of plants and Tricodesma lanicum is known under a similar English name "wild borage." The Latin names for the two plants differ: Tricodesma lanicum for wild borage, and Borago officinalis for borage. Although the art teaches the use of borage seed oil, as a source of GLA, Trichodesma lanicum or wild borage seed extract is not mentioned. Indeed, Trichodesma lanicum seed contains almost 5 times less GLA than borage seed. The unsaturated fatty acid constituency of Trichodesma lanicum seed and borage seed is very different:
______________________________________ BORAGE % TRICHODESMA CARBON CHAIN BY WEIGHT LANICUM % BY WEIGHT ______________________________________ 18:2 n-6 (Linoleic Acid) 38.8 18.7 18:3 n-6 (.gamma.-Linolenic Acid) 20.7 5.5 18:3 n-3 (.alpha.-Linolenic Acid) 0.5 24.7 18:4 n-3 (Stearidonic Acid) 0.1 6.5 ______________________________________
The art discussed above does not teach any compositions containing Trichodesma lanicum seed extract in combination with HAs and/or retinoids. The art does not appear to teach the use of Trichodesma lanicum seed extract or any of its constituent unsaturated fatty acids to reduce irritation or sting associated with the use of HAs and/or retinoids.